Pocket picking is an old art that is still avidly practiced in many parts of the world. As is a known fact, skilled pickpockets can pick a wallet out of a back pocket, even unbuttoning the back pocket, and sometimes out of a coat pocket, without the owner even being aware that physical contact has been made.
There are a number of ploys that are used to separate the mark from his wallet. For example, a team of two may work the revolving door of a department store or hotel. As the mark is on his way to the revolving door, the first member of the team begins walking in front of him, with the second member picking up the pace right behind the mark. Just as the first member of the team enters the door, he stops short as though he decided not to exit, causing the three bodies to collide together. The second team member separates the wallet from the mark during the impact, subsequent to which the team members are embarrassed and polite about the incident, and everyone goes their separate ways.
Because of ploys of this nature, and other techniques in which the mark is jostled unknowingly by pickpockets, it is difficult for a traveler to safeguard his wallet in conventional clothing. A rear trouser pocket having an enclosing flap and a button is no substantial deterrent for a skilled pickpocket team.
For this reason, money belts have been developed, and although somewhat awkward to use, do provide one of the best means of safeguarding against pickpockets. With a money belt, one is safe from all but muggers, inasmuch as it is inconceivable that even with a jostling ploy a pickpocket could get inside the money belt, unzip it, and extract folding money. However, the money belt is limited in that it is not a convenient place to store credit cards and the other things that are generally carried in a wallet. Money belts are not convenient places for cash. And even if the cash is all in the money belt, that does the traveler relatively little good if all of his identification and credit cards are stolen by a pickpocket not realizing there is no cash in the wallet.
There is a need, therefore, for some foiling device which would effectively retain the wallet in the pocket despite the efforts of eve the most skilled pickpocket or team of pickpockets.